Unwoven weftless ribbon and process for forming same



States UNWOVEN WEFTLESS RIBBON AND PROCESS FOR FORMING SAME No Drawing. Application August 18, 1953, Serial No. 375,048

Claims priority, application Great Britain September 9, 1952 2 Claims. (Cl. 154-92) This invention relates to fabrics and especially to weftless fabrics.

According to the present invention, weftless fabrics are made by bonding textile threads together by applying to a web of said threads a long-chain condensation polymer, the chains of which contain a major proportion of ester linkages and a minor proportion of amide linkages, and converting said polymer in situ into a rubbery polymer by cross-linking said chains.

An important application of the invention is in making ribbon-like materials for tying up small packages, for example chocolate boxes, for display and sale. Ribbonlike materials particularly suitable for this purpose can be made from a narrow warp of continuous-filament cellulose acetate yarns. Wider weftless fabrics may also be made, e. g. for use as showerbath curtains. Textile materials other than the cellulose acetate yarns described can be used and fabrics can also be made from assemblies of textile threads not arranged parallel to one another.

Preferably, the assembly of threads to which the bonding agent is applied is a warp (i. e. a sheet of yarns parallel to one another) composed of continuous-filament yarns, the warp being drawn continuously past the point at which the bonding agent is applied. The bonding agent preferably comprises, in solution in a volatile solvent, the condensation polymer and an agent or agents capable of effecting the desired cross-linkage at a temperature above that required to evaporate oh the solvent, but substantially inoperative at lower temperatures. The volatile solvent must not, of course, be of such nature as to damage the textile material. A slight swelling effect on that material may be of advantage. Thus, for example, the bonding agent and cross-linking agent may be applied in solution in a liquid or mixture of liquids having a boiling point or boiling range between about 50 and 100 C., and the cross-linking agent may be substantially without effect or relatively slow in action at temperatures up to 100 C., but capable of effecting the desired cross-linkage in five to fifteen minutes or even less at 120 to 150 C. After passing a region in which the bonding solution is applied (say at atmospheric temperature or slightly above) the coated warp may be carried in turn through a region where the solvent is evaporated at a higher temperature and then through a region at a still higher temperature where the cross-linkage is effected.

To obtain the desired properties in the cross-linked polymer, it is necessary that the chain-length of the polymer be very great; that the structure be not so regular to favour crystallim'ty or insolubility; and that the --NH atent groups be not unduly numerous. Such polymers can be obtained (as described, for example, in British Patent No. 553,733) by reacting upon a linear polyester or polyesteramide (both referred to below as the primary polymer) with a di-isocyanate so as to join primary polymer chains and to end by links containing a -CO.NH.R".NH.CO- group (where R" is a bivalent radical) derived from the di-isocyanate. Products obtained from the primary polymer in this way are termed di-isocyanate-modified polymers.

The primary polymer may be a polyester which is a derivative of two components only, viz., a dibasic acid and a dihydroxy compound. In this case the chain flexibility that is necessary is most readily obtainable with an aliphatic dicarboxylic acid, e. g. succinic, adipic or sebacic acid, rather than with a cyclic dicarboxylic acid such as terephthalic acid, and with a branched chain glycol, e. g. 1,2-propylene glycol rather than a straight-chain glycol, such as ethylene glycol or 1,3-propylene glycol or a cyclic dihydroxy compound such as hydroquinone. This flexibility is more easily obtained in polyesters which are derived from more than two components, e. g. from a dicarboxylic acid and two different glycols or from a dicarboxylic acid, a glycol and a hydroxy carboxylic acid. We have obtained the best results however, when the primary polymer is a polyesteramide derived, for instance, from a dibasic acid, preferably an aliphatic acid such as those specified above, a dihydroxy compound, preferably a glycol such as ethylene glycol or a propylene glycol, and a third bifunctional component containing amino groups. This third component may be adiamine, e. g. hexamethylene diamine or other w.w' polymethylene diamine, an amino alcohol, e. g. monoethanolamine or other primary amino alcohol, or an amino-carboxylic acid, e. g. 6-amino caproic acid or other w-amino paraflinic carboxylic acid. For reasons referred to above it will be understood that cyclic diamines, amino phenols and amino aromatic acids are less useful as the third component. The ester amide may be derived from other combinations of two or more components, e. g. amino-alcohols and dibasic acids; amino-acids, amino-alcohols and dibasic acids; and amino-alcohols, diamines and dibasic acids. The primary polymer should have an average molecular weight of at least 3,000 and preferably 4,000. Particularly useful as the primary polymer are long-chain condensation polymers the chains of which contain segments of molecular weight at least 4,000, and of the formula ORO-]m[OCR'cO--]n[NlR"O-]p, where R, R and R are bivalent paraffinic residues, and m, n, and p are whole numbers, m being 4 to 10 times p, and p+m being at least equal to n. R and R may with advantage be ethylene radicals, and R a tetramethylene radical, and m may be 4 to 6 times p, and n substantially equal to m+p. The primary polymer may, for example, he a condensation polymer of ethylene glycol, adipic acid and monoethanolamine in molar proportions of about 5:6: 1.

The di-isocyanate with which the primary polymer is modified should preferably be an aliphatic compound, e. g. ethylene di-isocyanate, 1,3-propylene di-isocyanate, 1,4-butylenedi-isocyanate or other w.w'-polyalkylene diisocyanate. 1,6-hexamethylene di-isocyanate is particu larly suitable. Cyclic di-isocyanates, e. g. p-phenylene di-isocyanate, p-cyclohexyl di-isocyanate, l,4-di-isocyano-.

methyl benzene, and 4,4'-di-isocyanomethyl diphenyl methane and 1,S-di-isocyanonaphthalene, are less suit able. The di-isocyanate-modified polymer should be of average molecular weight at least 20,000 and preferably at least 50,000.

Various cross-linking agents for polymers containing NH groups are available. The cross-linking of diisocyanate-modified polymers is described in British Patents Nos. 580,524 and 580,526. The cross-linking agent may be formaldehyde or a substance that is capable of liberating formaldehyde under appropriate conditions, or a substance containing one or more reactive methylol or substituted methylol groups. Particularly suitable for the purpose of the present invention are acetone-soluble resin-forming substances containing a plurality of methylol groups and/or methoxymethylol groups, e. g. the monomethyl and dimethyl ethers of dimethylol urea and especially the hexamethyl ether of hexamethylol melamine. Polyisocyanates and polyisothiocyanates may also be employed.

The cross-linking agent should preferably be substantially inoperative at the temperature at which coating of the assembly of threads is effected, but capable of rapid reaction when the coated assembly is heated to a suitable temperature. This condition is best satisfied by employing a cross-linking agent such as the melamine ether referred to (the action of which is very slow under neutral conditions at temperatures up to about 130 C. but is rapid at higher temperatures in the presence of acid), together with a substance that becomes acid at such higher temperatures. The use of such potentially acid accelerators is described in British Patent No. 580,526. Particularly suitable for the purpose of the present invention are acetone-soluble halogenated phenols, especially halogenated naphthols such as 2,4-dichloro-naphthol.

The boiling range of the volatile solvent should preferably be within the limits 50 to 140 C. so as to avoid, on the one hand, undue evaporation during application of the adhesive, and on the other hand the necessity of employing too high a temperature in removing the solvent. Solvents based on aliphatic ketones boiling within the range specified, and especially mixtures of methyl ethyl ketone with methyl isopropyl ketone or diethyl ketone, have been found particularly suitable with cellulose acetate threads. Swelling agents for cellulose acetate of appropriate boiling point such as the monoethyl ether of ethylene glycol may also be present with advantage. Only slightly inferior to the ternary mixture specified is the monoethyl ether of ethylene glycol alone, and this has the'advantage that solvent recovery is simplified. Other aliphatic ethers, as well as alcohols, having suitable boiling points, may be employed in formulating the volatile solvent. For bonding threads of cellulose (including regenerated cellulose) acetone, or mixtures of acetone with suitable diluents, may be used.

In formulating the compositions to be employed in bonding, it is preferable to use as little solvent as is consistent with obtaining a composition that can easily be spread on to the web to be coated. Thus the concentration of the polymer should preferably be between 30 and 50%, e. g. 40 to 50%, by weight of the total composition. The amount of cross-linking agent required in connection with a particular polymer depends on the constitution of the agent. With the hexamethyl ether of hexamethylol melamine, for example, useful results have been obtained with proportions ranging from about 3 to about 10%, and especially between 4 and 8%, based on the weight of the polymer. The composition may contain dyes, pigments and other effect materials. As indicated above, plasticizers are not generally necessary, but if for any reason a product of particularly soft handle is required, plasticizers may be incorporated. Suitable plasticizers for cellulose acetate include phthalates such as dimethyl, diethyl, dibutyl, di-(methoxyethyl) and the di- (methylcyclohexyl) phthalates, methyl phthalyl ethyl glycolate, ethyl phthalyl ethyl glycolate, butyl phthalyl,

butyl glycolate and liquid phosphoric acid aromatic esters such as tricresyl phosphate.

The following examples illustrate the invention. All the parts are by weight:

Example 1 A warp /z" wide, composed of ends of cellulose acetate yarn of 140 denier, having 12 /2 turns per inch, was impregnated with the following composition:

Parts by weight Vulcaprene AC. (a diisocyanate-modified polyesteramide) l4 Methyl ethyl ketone 60 Methyl isobutyl ketone 26 Vulcafor VHM (a substance containing reactive substituted methylol groups) 0.7 Vulcafor VDC (a potentially acid substance) 0.1

The impregnation was carried out at 35 C. and so as to leave a quantity of solids equal to about 25% of the final weight of the finished ribbon. The impregnated warp was then dried and vulcanized in an oven at C. for 10 minutes.

Example 2 A warp /8 wide, composed of 120 ends cellulose acetate yarn of denier, having 10 turns per inch, was impregnated with the following composition:

The impregnation and subsequent treatment were carried out as described in Example 1.

Instead of the solvent mixture specified, equal parts of methyl ethyl ketone and toluene, or of ethylene dichloride and benzene, or of ethyl lactate and benzene, can be employed.

Example 3 The process was carried out as in Example 2, but using as the textile material 120 ends of a regenerated cellulose yarn of tenacity 4 gms. per denier, of denier 150 and twist 5 turns per inch, and as the solvent 150 parts of acetone.

The textile threads to be coated may, of course, be coloured by means of pigments or dyestuffs, and such colouring may be uniform or local. Again, the bonding composition may contain colouring matters which may be the same colour as that carried by the threads, or may be in a contrasting colour. Further ornamental effects maybe produced by embossing, crimping or metallizing the ribbons or fabrics.

By the process of the invention, weftless ribbons and wettless fabrics may be produced which are water-rcsistant and which have quite considerable strength across the warp. The ribbons are very useful for tying packages and for other display purposes. The ribbons may be produced by impregnation of a narrow warp or by impregnation of a wide warp of thread followed by slitting the fabric thus produced in a warpwise direction. The fabrics themselves, due to their lateral strength, find certain applications apart from being useful for slitting into ribbons. Thus they may be used for bathroom curtains, showerbath curtains and in other applications where water-resistance is important and lateral strength is desirable.

Having described our invention, what we desire to secure by Letters Patent is:

1. An unwoven self-supporting ribbon consisting of a web of parallel cellulose acetate yarns, bonded together by an adhesive composition comprising a 1,6 hexamethylene diisocyanate-modified condensation polymer of ethylene glycol, adipic acid, and monoethanolamine in molar proportions of 5:6:1, cross-linked by means of the hexamethyl ether of hexarnethylol melamine.

2. Process for forming a weftless ribbon which comprises bonding together yarns of a Warp consisting of parallel cellulose acetate yarns to form a self-supporting web, by applying to the web a solution, in a volatile solvent that does not dissolve cellulose acetate, of a 1,6-hexamethylene diisocyanate-modified condensation polymer of ethylene glycol, adipic acid, and monoethanolamine in molar proportions of 5:6:1, together 6 with 2,4-dichloro-naphtho1 and the hexamethyl ether of hexamethylol melamine, evaporating off the solvent, and heating to convert the polymer into a cross-linked rubbery state.

References Cited in the file of this patent UNITED STATES PATENTS 1,992,665 Hazell Feb. 26, 1935 2,055,821 Hansen et al. Sept. 29, 1936 2,333,917 Christ et a1. Nov. 9, 1943 2,441,071 Jahant May 4, 1948 2,650,212 Windemuth Aug. 25, 1953 2,734,012 Downing Feb. 7, 1956 FOREIGN PATENTS 580,524 Great Britain Sept. 11, 1946 580,525 Great Britain Sept. 11, 1946 

2. PROCESS FOR FORMING A WEFTLESS RIBBON WHICH COMPRISES BONDING TOGETHER YARNS OF A WARP CONSISTING OF PARALLEL CELLULOSE ACETATE YARNS TO FORM A SELF-SUPPORTING WEB, BY APPLYING TO THE WEB A SOLUTION, IN A VOLATILE SOLVENT THAT DOES NOT DISSOLVE CELLULOES ACETATE, OF A 1,6-HEXAMETHYLENE DIISOCYANATE-MODIFIED CONDENSATION POLYMER OF ETHYLENE GLYCOL, ADIPIC ACID, AND MONOETHANOLAMINE IN MOLAR PROPORTIONS OF 5:6:1, TOGETHER WITH 2,4-DICHLORO-NAPHTHOL AND THE HEXAMETHYL ETHER OF HEXAMETHYLOL MELAMINE, EVAPORATING OFF THE SOLVENT, AND HEATING TO CONVERT THE POLYMER INTO A CROSS-LINKED RUBBERY STATE. 